PETERBOROUGH — Workers returned to most of the New Hampshire Ball Bearings plant on Thursday and Friday, following the Monday's explosion that has left two injured employees hospitalized.

On Thursday, a statement on the company’s website about the two workers said, “We understand that both are in critical but stable conditions and that their recovery will be long and difficult. Please continue to keep them in your thoughts and prayers.”

Company officials have declined to release the names of the hospitalized employees or any other information about the extent of their injuries, citing concern for their privacy.

On Thursday, 525 employees returned to work, on all three shifts. The company employs 745 people. The company’s ball inspection department, ball plant, press room/retainer and assembly departments remained closed while clean up work continued.

NHBB President Gary Youmantis flew in from the company’s headquarters in California and met with workers on Thursday.

On Friday, company spokesperson Hans Baker said the company was working closely with customers to keep them informed about lead times and delivery schedules. He said having the factory shut for a few days should not have a long-term impact. Baker said moving work to other company plants would be more complicated and time-consuming than quickly repairing the damage to the Peterborough building.